Heteroschizomus Rowland, 1973

Monjaraz-Ruedas, Rodrigo, Prendini, Lorenzo & Francke, Oscar F., 2019, Systematics Of The Short-Tailed Whipscorpion Genus Stenochrus Chamberlin, 1922 (Schizomida: Hubbardiidae), With Descriptions Of Six New Genera And Five New Species, Bulletin of the American Museum of Natural History 2019 (435), pp. 1-93 : 44-45

Heteroschizomus Rowland, 1973 , stat. rev.

Figures 4 , 6, 7E, 8E, F, 11C, 13E, 18C, D, 19D– F, 21A–F; tables 1, 2, 7

Heteroschizomus Rowland, 1973a: 1 , 2, 4; 1973b: 197; Rowland and Reddell, 1977: 83; Martín and Oromí, 1984: 266; Reddell and Cokendolpher, 1991: 3, 5, 18.

Stenochrus (part): Reddell and Cokendolpher, 1991: 1, 3.

Schizomus goodnightorum group: Rowland 1975b: 37, 39, 167, 168, 255, 256, 258, 259, 263, 265, 267, 320, 321, 325, 348–350, 376, 390, 397; Rowland and Reddell, 1979a: 165, 171; 1979b: 90; 1980: 3; Reddell, 1981: 126; Rowland and Reddell, 1981: 19–21, 23–25, 27; Reddell and Cokendolpher, 1991: 1, 3; 1995: 101, 102; Villarreal et al., 2008: 64, 67; Moreno-González and Villarreal, 2012: 73; Villarreal and García, 2012: 5; Villarreal et al., 2014: 371; Monjaraz-Ruedas and Francke, 2015: 452; 2016: 781, 783; 2018: 189, 212.

TYPE SPECIES: Heteroschizomus goodnightorum Rowland, 1973 , by original designation.

DIAGNOSIS: Heteroschizomus , stat rev., may be separated from other hubbardiid genera by the following combination of characters. Cheliceral movable finger with lamella (fig. 12 C) ; single guard tooth at end of serrula; setal group G3 with G3-3 setae situated anteriorly (except in Heteroschizomus silvino ( Rowland and Reddell, 1977) , comb. nov.) (fig. 13E). Propeltidium anterior process with two anterior setae (one posterior to the other) and three or four pairs of dorsosubmedian setae (fig. 11 C) ; corneate eyes absent. Metapeltidium entire. Tegument without clavate setae. Pedipalps homeomorphic ; trochanter with small prolateral spur, apical process acute and not projected (fig. 7E); femur Fv 1 and Fv 2 setae acuminate, Fvr 1–3 setae present ; patella with three acuminate Pe setae and three or four feathered Pm setae ; tibial setal formula 3-3-4 (Ter-Tmr-Tir) (fig. 14D). Leg IV femur anterodorsal margin produced at ca. 90° angle. Opisthosomal tergite II with one pair of setae (Dm). Opisthosomal segments IX–XII (♂) elongated (fig. 18 C) ; XII (♂) without posterodorsal abdominal process. Pygidial flagellum (♂) dorsoventrally flattened, spatulate, with well-defined anterior bulb and posterior constriction in dorsal view, and with pair of anterodorsal pits (except H. goodnightorum and Heteroschizomus meambar (Armas and Víquez, 2010) , comb. nov., with single median depression) (fig. 19D–F); flagellum (♀) with two annuli (fig. 21A–F). Spermathecae (♀) with two pairs of lobes, similar in length and width; both pairs of lobes linear with apex directed vertically, unsclerotized (fig. 8E, F); lobes without bulbs; median lobe bases variably situated with respect to lateral lobe bases, without duct openings; chitinized arch mug shaped, with wide, sclerotized base (fig. 8E, F); anterior branch curved, unfused medially, with lateral tips wide, curved, and lobed; gonopod wide and short.

COMPARISONS: Species of Heteroschizomus , stat. rev., resemble species of Piaroa in many aspects of the male morphology and, without females, it is almost impossible to differentiate between them. However, a combination of subtle characters concerning the cheliceral movable finger, the apical process of the pedipalp trochanter, and the number of dorsal setae on the propeltidium enable the males of these genera to be differentiated. The number of dorsal setae on the propeltidium is the most obvious difference between the males of Heteroschizomus and Piaroa . Although the original description of Piaroa mentioned three pairs of dorsal setae ( Villarreal et al., 2008), this count included the anterior pair. The correct count for Piaroa is two pairs, as observed in all its component species, except Piaroa youngi Armas and Víquez, 2010 , which exhibits three. In contrast, the male of Heteroschizomus bears more than three pairs. Additionally, the cheliceral movable finger of the male bears a small lamella in Heteroschizomus but is smooth or bears teeth or a lamella in Piaroa . The pedipalp trochanter apical process is acute but not projected or forms a small protuberance in the male of Heteroschizomus , but triangular or conical, and projected in the male of Piaroa (except for Piaroa escalerette Moreno- Gonzalez et al., 2014). Despite the similarity between males of Heteroschizomus and Piaroa , the females of both genera are markedly different. Correct assignment to genus is therefore best achieved with specimens of both sexes. The female pygidial flagellum possesses two annuli in Heteroschizomus , but three annuli in Piaroa ; and the female spermathecae possess two pairs of lobes, a mug-shaped chitinized arch, and gonopods in Heteroschizomus , whereas only one pair of lobes and a mask-shaped chitinized arch are present, and gonopods absent in Piaroa .

INCLUDED SPECIES: Heteroschizomus goodnightorum Rowland, 1973 ; Heteroschizomus kekchi , sp. nov.; Heteroschizomus meambar (Armas and Víquez, 2010) , comb. nov.; Heteroschizomus orthoplax ( Rowland, 1973a) , comb. nov.; Heteroschizomus silvino ( Rowland and Reddell, 1977) , comb. nov.

DISTRIBUTION: The distribution of Heteroschizomus , stat. rev., extends from the state of Chiapas in southern Mexico southward to Honduras. The southernmost record of the genus is H. meambar , comb. nov. There are no records of Heteroschizomus in Costa Rica and Nicaragua, but the northernmost record of Piaroa , i.e., Piaroa bijagua Armas and Víquez, 2009 , is from Costa Rica, suggesting the two genera converge and possibly overlap in Nicaragua. More sampling efforts are needed to clarify the distributions of Central American schizomids (fig. 4).

NATURAL HISTORY: Species of Heteroschizomus , stat. rev., are primarily epigean, except for H. silvino , comb. nov., a cavernicolous species. Specimens of H. goodnightorum have been found near, but not inside, caves in the Yucatán Peninsula. Species of Heteroschizomus exhibit a unique way of walking that is faster than has been observed in other Mexican schizomids, with the elongated opisthosoma flipped over above the prosoma, like ants of the genus Crematogaster Lund, 1831 . This has not been reported in other schizomid genera with an elongated opisthosoma, i.e., Colombiazomus Armas and Delgado-Santa, 2012 , Hansenochrus , and Piaroa .

REMARKS: The revalidation of Heteroschizomus , stat. rev., is based in part on the discovery of the female of H. goodnightorum . Rowland and Reddell (1981) misidentified a female of Stenochrus portoricensis , which occurs in sympatry in the Yucatán Peninsula, as the female of H. goodnightorum . The female spermathecae are similar in H. goodnightorum and H. silvino , comb. nov., and although the female of H. orthoplax , comb. nov., remains unknown, the description of H. kekchi , sp. nov., confirms the diagnostic morphology of the spermathecae of

Figures

FIG. 4. Map of southern Mexico, plotting known locality records for the short-tailed whipscorpion genera Heteroschizomus Rowland, 1973, stat. rev. (circles), and Troglostenochrus, gen. nov. (squares) (Schizomida: Hubbardiidae Cook, 1899), based on data from museum collections and the literature.